The invention relates to a door hinge with an integrated door stop for a vehicle door.
If a motor vehicle door is to be fixed in a certain opening position, a door stop is used for this purpose. Door stops which are integrated in door hinges provide compact solutions in this regard. German Offenlegungsschrift DE 198 11 108 to A1 discloses a door hinge, which is described at the beginning, with an integrated door stop, in which the door stop comprises a spring element which engages in latching positions on a driver plate and the door hinge part (door console) is connected in a rotationally fixed manner to the hinge shaft (hinge pin) and the hinge shaft is connected in a rotationally fixed manner to the driver plate. In the case of a door stop of this type, which uses a very large, S-shaped torsion spring as spring element, the door can only be fixed at door position angles predetermined by the latching positions.
The door hinge with an integrated door stop is disclosed in German Patent Application No. 44 26 425, in which a hinge part arranged at the door and a hinge part arranged at the car body are pivotally connected by a bearing. A profile disc is formed and arranged like a pitch circle around the bearing, the profile of which shows radially extending elevations and depressions between it on the side opposite of the swicelling bearing. A roller is arranged at the top of a convex gliding part in such a manner that it is prestressed by a compression spring and pressed radially against the profile. A braking and holding momentum is exercised on the door part by the engagement of the roller into the depressions of the profile.
The technical problem on which the invention is based is to construct a hinge with an integrated door stop which permits an infinitely variable fixing of the door in any desired opening position and permits the motor vehicle door to be moved from the opening position and after any desired stop both in the opening and in the closing direction just using a predetermined force.
In the case of the proposed door stop, the braking or retaining moment for the motor vehicle door is applied by a frictional moment between the two hinge parts. To this end, the pressure ram, which is guided radially in the hinge part with a running fit, and the circumferential profiling of the hinge shaft, which is fixed in a rotationally secure manner with respect to the other hinge part, interact. In the process, the required frictional force is produced by a spring and is determined by the selection of the spring chararacteristic. If the door is to be opened by up to 90xc2x0 in a manner such that it can be fixed, the circumferential profiling of the hinge shaft has to be arranged at least on a quarter of the shaft circumference in the region of the possible effectiveness of the pressure ram and therefore of the projection of the radial hole. The profiling has contours, the distance of which from the shaft axis is smaller than the shaft radius, with the result that the spring-loaded pressure ram moves forward in contact with the profiled contour and therefore fixes the shaft with respect to neighboring contours at a greater distance from the shaft axis and with higher frictional force. If the non-profiled circumferential section of the hinge shaft extends over more than half of the shaft circumference, the shaft is reliably guided peripherally in the gudgeon.
Depending on the desired fixing characteristic, the profiling can have different contours. If the door is to be fixed in an infinitely variable manner, the transitions between the sectors at a different distance from the shaft axis have to be continuous with minimal differences in distance. The transitions have therefore to be gentle or progressive or gradual.
In embodiments, in which the profiling of the hinge shaft in a number of sectors situated peripherally next to one another have contours which are matched to the profile of that end surface of the pressure ram which interacts in each case with the contour, the contour of the end surface of the pressure ram for the infinitely variable fixing within latching regions has also to be designed as a contour which only changes in a gentle manner, or is a planar contour.
In an embodiment, in which the contours of the profiling of the shaft circumference have, for at least one sector, a graduated circle contour having a respectively smaller radius in comparison with the front sector in the opening direction of rotation of the door, the door can be fixed in an infinitely variable manner in every opening or closing position if the frictional force between the pressure rams and hinge shaft is set appropriately. In this case, the profile of the pressure ram end surface is plane and parallel to the shaft axis. The door is fixed in an infinitely variable manner in every desired position as soon as the frictional force between the pressure ram and hinge shaft has been appropriately set. If the radius of the sector corresponding to the closing position is smaller by at least the spring travel of the compression spring than the radius of the adjacent sector, the compression spring is relaxed in the closing position, with the result that the threaded cylinder can advantageously be set in the closing position with a very low torque.
It has been shown in tests that the interacting contact sections on the pressure ram end and the graduated circle contour of the shaft circumference are not subject to any particular wear. This is firstly because the contact sections are relatively large, but secondly and especially also because the pressure ram always rotates about its own axis when acting on the shaft surface. This rotation is to be attributed to the fact that in spite of exact dimensions and installation dimensions extremely small tolerances are in play and therefore have the effect that the forces between the respectively symmetrical sections of the interacting parts are not absolutely the same and not nullify one another.
The introduction of a central blind hole in the end surface of the pressure ram has an advantageous effect on the wear behavior. If the blind hole is arranged offset eccentrically by less than its radius, this assists the rotation of the pressure ram about its own axis, since the difference between the contact sections on both sides of the blind hole reinforces the heterogeneity of the compressive forces in a specific manner.
An exemplary embodiment, in which the hinge shaft has, in the central section in which the circumferential profiling is also arranged, an axially running outer profile and an external sleeve which has an inner profile matched in a form-fitting manner to the outer profile of the shaft, has the advantage that the hinge shaft does not have to be machined in its entirety in order to apply the circumferential profile. Particularly if that subsection of the sleeve which has the circumferential profiling is a single-piece latching sleeve, the circumferential profiling can be restricted to this latching sleeve. The latching sleeve is then only of the length which corresponds to the corresponding extent of the pressure ram. If the central section of the hinge shaft is of longer length, corresponding sleeve sections having a circular circumference can also be arranged on both sides of the latching sleeve. If the latching profile is to be changed, the latching sleeve has merely to be interchanged in order to achieve this. This construction also permits the best suited material in each case or the most cost-effective material which is suitable for the particular requirements to be selected for the particular regions of hinge shaft and sleeves.
An exemplary embodiment, in which the compression spring has a central opening into which a pin, which is arranged on the end of the threaded cylinder or in the back of the pressure ram, protrudes flush with the edge, in which case a recess corresponding to the cross section of the pin is present in the respective other part without a pin, has the advantage that the compression spring is guided exactly in the radial hole, with the result that tilting of the compression spring and a nonuniform transmission of the spring force is avoided.
In one embodiment, in which the radial hole, which is accessible from the outside of the hinge tab, is arranged in the threaded cylinder with a screw profile which is accessible from outside, the threaded cylinder can also be adjusted in the installed state. Appropriate setting of the threaded cylinder causes the compression spring to be prestressed as desired and thereby enables the level of spring force to be appropriately changed. If, on the door assembly part to which the hinge part is fastened with a running fit, a motor is arranged in such a manner that its drive shaft engages, by means of a driver, into the screw profile of the threaded cylinder, this has the advantage that the level of spring force can be changed by motor.